A constant trend in the mobile communication market is the ongoing development towards miniaturization. However, operability requires certain minimum sizes for components with which a user must interact, such as its keypad or display. Therefore, certain designs of mobile communication devices include folding or sliding mechanisms. These designs allow smaller sizes when the device is not in operation and can also provide an additional protection for keypad and display.
For example, U.K. Patent Application GB2235606A is directed to a portable telephone provided with an extending sleeve-like portion mounted for longitudinal slidable movement between a retracted position when not in use and an extended position for use. The extending portion can be adapted to conceal selected keys of a keypad in the retracted position to prevent accidental actuation of the these keys. U.K. Patent Application GB2235606A is directed to a retaining structure for holding the extending portion in the retracted position. When a release button is pressed, the extending portion is automatically moved to the extended position under the action of a spring.
U.K. patent application GB2235606 is directed to a release mechanism. Unfortunately, its design is such that it is vulnerable to opening by itself, for example when being carried in a rucksack together with other things. Other slider mechanisms adapted for manually performing the sliding movement, have the same problem.
This is not a minor problem, because when an electronic device is activated, its power consumption increases. For example, when a portable telephone is activated, its backlight typically turns on, resulting in a dramatically increased power consumption. Since the sliding mechanism typically is adapted to conceal the keypad or parts thereof, unintentional opening of the slider mechanism can also result in unintentional depressing of keys and unintended activation of functions. Unwanted calls to emergency response numbers may even result.
U.S. Pat. No. 5,241,583 is directed to a portable radio telephone provided with an electronic keypad lock function for disabling the keys to prevent accidental actuation. The keypad is disabled and enabled by performing a predetermined order of keystrokes. The patent also discloses a variation in which the keypad automatically unlocks upon detecting an incoming call.
Disabling the keypad, however, does not solve the problem of increased power consumption due to a backlight switched on by an accidentally opening slider mechanism. What is needed in the art is a fundamentally new way to lock mobile communication devices to prevent unintentional activation.